Today’s transactional systems make the concept of real-time updates a reality. Such updates are mandatory for systems like online ordering, where prospective customers want to know whether an item is in stock. However, for other systems—financial systems in particular—real-time updates create challenges when comparing the value of a set of transactions on one system with the value of the duplicate transactions on another system. The values must match; if they do not, someone must track down the issue. We all have struggled with balancing a personal checking account statement, and these systems are no different, except that the scale of the challenge can be much, much more significant.